I. Field
The present disclosure relates generally to wireless communications, and more specifically to techniques for transmitting data in a wireless communication system.
II. Background
Wireless communication systems are widely deployed to provide various communication services; for instance, voice, video, packet data, broadcast, and messaging services may be provided via such wireless communication systems. These systems may be multiple-access systems that are capable of supporting communication for multiple terminals by sharing available system resources. Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, and Orthogonal Frequency Division Multiple Access (OFDMA) systems.
Traditionally, a wireless communication system, also referred to as an access network (AN), utilizes either frequency division duplexing (FDD) or time division duplexing (TDD) for data transmission between base stations and terminals (e.g., access terminals or ATs) on the forward and reverse links. The forward link (or “downlink”) refers to the communication link from the base stations to one or more terminals, while the reverse link (or “uplink”) refers to the communication link from a terminal to one or more base stations. In a wireless communication system utilizing FDD, separate frequency channels are used for the forward and reverse links. A terminal may simultaneously receive data on a forward link (FL) frequency channel and transmit data on a reverse link (RL) frequency channel. In contrast, in a wireless communication system utilizing TDD, a single frequency channel is used for both the forward and reverse links. The transmission timeline in such a system is partitioned into time intervals, with certain time intervals being used for FL transmission and other time intervals being used for RL transmission. Based on this partitioning, a terminal may transmit data on the frequency channel in time intervals reserved for RL transmission and may receive data in time intervals reserved for FL transmission.
A terminal designed for operation in an FDD system is able to receive and transmit at the same time by using a duplexer, which assigns FL communications and RL communications different frequency bands to allow simultaneous FL and RL communication. However, a terminal may be designed for operation in a TDD system and may lack a duplexer to allow the terminal to receive and transmit at the same time. Thus, the terminal would not be able to operate in a typical FDD system that supports simultaneous transmission and reception on two frequency channels. Further, duplexers can be costly to implement and as a result may not be desirable for some terminals in an access network. In addition, it has traditionally been difficult to build a duplexer for a terminal that operates in a high-bandwidth access network that cleanly separates two frequency bands due to the high bandwidth of the network.